1966 L72 fuel pump and pump to Y-block line

[Geoff Germane]

I have an early 427/425 with probably a non-original fuel pump. The fuel line to the Y-block (probably non-original) exits the pump with a very short horizontal section, followed by a long vertical section. The replacement line that I obtained is designed to attach to the pump in a vertical orientation, with a 3/8 inverted flare fitting. Several suppliers show the same diagram for the line for the L72. However, the fuel pump outlet is an inverted flare with a horizontal orientation. It appears that an adapter is needed -- the 90 deg. elbow that several suppliers have is a 1/4 pipe by 3/8 inverted flare. I cannot believe that GM intended the pump outlet inverted flare fitting to receive a pipe threaded fitting in order to turn the corner for the vertical steel fuel line. I seem to be missing some information? Are the replacement fuel lines incorrect? I have gleaned from the archives that all 1966 big block fuel pumps contained a crimped fuel cannister, suggesting that the outlet fittings are not threaded into the pump. What kind of outlet fittings were available other than horizontal inverted flare, if any? Sorry for the long post. Thanks in advance for any help.

[Mike M.]

Re: 1966 L72 fuel pump and pump to Y-block line

sounds like you have a 67 bb fuel pump which used a different setup at the outlet fitting on the pump, compared to the 65 and 66 bb pumps. mike

[Mark #28455]

not a hardware store 90 deg elbow

When the factory used a 90 degree elbow that threaded into a flared fitting, the elbow had a 45 degree flare machined into it to properly seat in the flared fitting and allow the 45 degree flare to do the sealing.
Mark

[Geoff Germane]

Re: not a hardware store 90 deg elbow

Thanks for the useful detail, Mark. Am I to understand that the 90 deg. elbow contains a 1/4 in. pipe thread with a machined 45 deg. mating surface, or is it a straight thread that is compatible with the 3/8 in. inverted flare threads, with a machined mating surface to accomplish the sealing?

[Michael H.]

Re: not a hardware store 90 deg elbow

Geoff,

Here's a pic of the correct #137423 65-66 big block fuel pump 90* outlet fitting. It's 1/4" pipe on the pump side and machine thread with tapered seat on the outlet side. Hope this helps.

[Geoff Germane]

Re: 90 deg elbow question -- closing in on answer

Thanks, Michael. The photograph does help. I cannot detect any difference between the fitting in the photograph and a garden-variety 1/4 NPT -- 3/8 inverted flare brass fitting available from any parts store. What is the pump interface for the fitting shown in the picture? Is it a 1/4 NPT female outlet, or is it a female 3/8 inverted flare? Thanks in advance.

[Michael H.]

Re: 90 deg elbow question -- closing in on answer

Geoff,

Yes, you are correct. The 90* fitting is not special and can be found at any auto parts etc., although it may look slightly different. (wrench size)

The female outlet on a 65-66 fuel pump is also 1/4" pipe thread without a seat.

[Geoff Germane]

Re: 90 deg elbow question -- closing in on answer

Thanks again, Michael. Is the female 1/4 NPT in a brass block that is attached to a stamped fuel cannister, or is it a threaded bore in the cast aluminum fuel pump housing? Thanks in advance.

[Joe L.]

Re: 90 deg elbow question -- closing in on answer

Geoff-----

It's neither, but you're close when you say "....brass block attached to a stamped fuel cannister...". The fuel outlet fitting on most of the "crimp type" fuel pumps is a STEEL fitting which is welded to the lower, stamped steel section of the pump. The orientation of this fitting relative to the fuel pump mounting flange AND the fuel inlet (usually a hose nipple) is what accounts for much of the reason for the vast array of fuel pump part numbers, for pumps that are otherwise similar in functional configuration.

Most outlet fittings are 3/8" tube fittings. However, for the 66-67 Corvette pumps, the outlet fitting is 1/4" NPT (referred to as 1/4" Dryseal by GM).